The present invention relates to a vehicle wheel testing device for detecting the alignment of a vehicle wheel rotating at a testing speed, and in particular, to a toe-in tester for detecting the toe-in of a wheel of a vehicle as the vehicle moves along a production line.
Prior art vehicle wheel alignment testing devices are known for detecting the toe-in and/or camber angles of vehicle wheels while the vehicle wheels rotate at a testing speed on a pair of support rollers. These prior art testing devices typically comprise a sensor plate with or without a plurality of rollers that is mounted in the device for relative movement and is initially brought into contact with the vehicle wheel. The wheel is then rotated and accelerated. As the wheels begin rotating, the toe-in of the wheels causes the vehicle to shift laterally on the support rollers until the vehicle becomes disposed at a testing position. Once the vehicle is in the testing position, relative movement of the sensor plate and/or rollers mounted thereto is then sensed to determine the toe-in and/or camber angles of the vehicle wheel.
However, a problem in these prior art devices results from the fact that, since a relatively large force is exerted on the vehicle wheels by the sensor plate and/or rollers prior to acceleration of the vehicle wheels, when the wheels begin accelerating, the lateral movement of the vehicle wheels on the support rollers toward the testing position is inhibited. As a result, in the prior art devices, it takes at least one minute for the vehicle wheel to reach the testing position after the sensor plate and/or rollers have been urged into contact with the vehicle wheel during a set-up stage. Such is not suitable for testing the wheels of a vehicle which is traveling along a high speed production line.